Fuel pump override control method

Abstract

A system and method of controlling a fuel system on an aircraft includes selectively supplying fuel from either a main fuel tank or at least one wing fuel tank to a fuel consumer by varying a speed of at least one main fuel tank pump associated with the main fuel tank relative to a speed of at least one wing fuel tank pump associated with the at least one wing fuel tank.

The invention claimed is: 
     
       1. A method of controlling a fuel system on an aircraft, the method comprising:
 determining whether the aircraft is above a predetermined altitude; 
 when the aircraft is above the predetermined altitude, operating at least one main fuel tank pump associated with a main fuel tank at a high-speed mode and at least one wing fuel tank pump at a low-speed mode to deliver fuel to a fuel consumer only from the main fuel tank until the main fuel tank is depleted; wherein the high-speed mode of the at least one main fuel tank pump corresponds to a nonzero speed and the low-speed mode of the at least one wing fuel tank corresponds to a nonzero speed that is less than the nonzero speed of the at least one main fuel tank pump; and 
 when the main fuel tank is depleted, operating the at least one wing fuel tank pump at a high speed mode and the at least one main fuel tank pump at a low-speed mode to deliver the fuel to the fuel consumer only from the at least one wing fuel tank; wherein the high-speed mode of the at least wing fuel tank pump corresponds to a nonzero speed and the low-speed mode of the at least one main fuel tank pump corresponds to a speed that is less than the nonzero speed of the at least one wing fuel tank pump. 
 
     
     
       2. The method according to  claim 1 , wherein the at least one main fuel tank pump and the at least one wing tank fuel pump are fluidically coupled to the same fuel consumer through a common fuel line, and selection of fuel from the main fuel tank or the at least one wing fuel tank is based on a fluid pressure created by the respective fuel tank pumps, the pressure created by each fuel tank pump corresponding to a speed of the respective fuel tank pump. 
     
     
       3. The method according to  claim 1 , wherein selectively supplying fuel comprises, when the aircraft is below the predetermined altitude, turning off the at least one main fuel tank pump and operating the at least one wing fuel tank at the high-speed mode corresponding to a nonzero speed to deliver the fuel to the fuel consumer only from the at least one wing fuel tank. 
     
     
       4. The method according to  claim 1 , further comprising turning off the at least one main fuel tank pump upon the fuel in the main fuel tank being depleted. 
     
     
       5. An aircraft fuel system for an aircraft, comprising:
 a main fuel tank including at least one main fuel tank pump; 
 a first wing fuel tank including at least one first wing fuel tank pump; and 
 a controller operably coupled to the at least one main fuel tank pump and the at least one first wing fuel tank pump, the controller configured to:
 determine whether the aircraft is above a predetermined altitude; 
 when the aircraft is above the predetermined altitude, operate at least one main fuel tank pump associated with a main fuel tank at a high-speed mode and at least one wing fuel tank pump at a low-speed mode to deliver fuel to a fuel consumer only from the main fuel tank until the main fuel tank is depleted; wherein the high-speed mode of the at least one main fuel tank pump corresponds to a nonzero speed and the low-speed mode of the at least one wing fuel tank corresponds to a nonzero speed that is less than the nonzero speed of the at least one main fuel tank pump; and 
 when the main fuel tank is depleted, operate the at least one wing fuel tank pump at a high speed mode and the at least one main fuel tank pump at a low-speed mode to deliver the fuel to the fuel consumer only from the at least one wing fuel tank; wherein the high-speed mode of the at least wing fuel tank pump corresponds to a nonzero speed and the low-speed mode of the at least one main fuel tank pump corresponds to a speed that is less than the nonzero speed of the at least one wing fuel tank pump. 
 
 
     
     
       6. The aircraft fuel system according to  claim 5 , wherein the at least one main fuel tank pump and the at least one first wing fuel tank pump are fluidically coupled to the same fuel consumer through a common fuel line, wherein selection of fuel from the main fuel tank or the at least one wing fuel tank is based on a fluid pressure created by the respective fuel tank pumps, the pressure created by each fuel tank pump corresponding to a speed of the respective fuel tank pump. 
     
     
       7. The aircraft fuel system according to  claim 5 , wherein the at least one main fuel tank pump and the at least one first wing fuel tank pump comprise a pump having the same specifications. 
     
     
       8. The aircraft fuel system according to  claim 5 , wherein the at least one main fuel tank pump and the first wing fuel tank pump each have the same physical dimensions and the same performance characteristics. 
     
     
       9. The aircraft fuel system according to  claim 5 , wherein the at least one fuel consumer comprises a first fuel consumer and a second fuel consumer, further comprising a first fuel line coupling the at least one main fuel tank pump and the at least one first wing fuel tank pump to the first fuel consumer, and a second fuel line coupling the at least one main fuel tank pump and the at least one second wing fuel tank pump to the second fuel consumer. 
     
     
       10. The aircraft fuel system according to  claim 9 , wherein the at least one main fuel tank pump comprises a first main fuel tank pump and a second main fuel tank pump, further comprising a cross-feed valve fluidically coupling the first main fuel tank pump to the second main fuel tank pump. 
     
     
       11. The aircraft fuel system according to  claim 5 , wherein the fuel consumer comprises a jet engine or an auxiliary power unit. 
     
     
       12. The aircraft fuel system according to  claim 5 , wherein the controller is configured to, when the aircraft is below the predetermined altitude, turn off the at least one main fuel tank pump and operate the at least one wing fuel tank at the high-speed mode corresponding to a nonzero speed to deliver the fuel to the fuel consumer only from the at least one wing fuel tank. 
     
     
       13. The aircraft fuel system according to  claim 5 , wherein the controller is configured to turn off the at least one main fuel tank pump upon the fuel in the main fuel tank being depleted. 
     
     
       14. A method of controlling a fuel system on an aircraft, the method comprising:
 simultaneously operating a wing fuel tank pump associated with a wing fuel tank fluidically coupled to an aircraft engine at a first nonzero operational speed and a main fuel tank pump associated with a main fuel tank fluidically coupled to the aircraft engine at a second nonzero speed that is different than the first nonzero operational speed to selectively deliver fuel to the aircraft engine solely from the wing fuel tank or solely from the main fuel tank. 
 
     
     
       15. The method according to  claim 14 , wherein the first nonzero operational speed is higher than the second nonzero operational speed such that fuel is delivered to the aircraft engine solely from the wing fuel tank. 
     
     
       16. The method according to  claim 15 , further comprising increasing the second nonzero operational speed to a nonzero operational speed that is higher than the first nonzero operational speed to override the wing fuel tank pump with the main fuel tank pump such that the fuel is delivered to the aircraft engine solely from the main fuel tank. 
     
     
       17. The method according to  claim 16 , wherein increasing the second nonzero operational speed to a nonzero operational speed that is higher than the first nonzero operational speed to override the wing fuel tank pump with the main fuel tank pump such that the fuel is delivered to the aircraft engine solely from the main fuel tank occurs when the aircraft is above a predetermined altitude. 
     
     
       18. The method according to  claim 16 , further comprising maintaining override of the wing fuel tank pump by the main fuel tank pump until the main fuel tank is depleted. 
     
     
       19. The method according to  claim 18 , further comprising turning off the main fuel tank upon the fuel in the main fuel tank being depleted. 
     
     
       20. The method according to  claim 15 , further comprising, when the aircraft is below a predetermined altitude, turning off the main fuel tank pump and operating the wing fuel tank pump at the first nonzero operational speed such that the fuel is delivered to the aircraft engine solely from the wing fuel tank.